From 58811fd0f7312b5f6dffd6a252bc1d68e25cfa01 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin@martin.st>
Date: Mon, 2 Aug 2021 13:47:40 +0300
Subject: [PATCH] [clang] [MinGW] Let the last of -mconsole/-mwindows have
 effect

Don't just check for the existence of one, but check which one was
specified last, if any.

This fixes https://llvm.org/PR51296.

Differential Revision: https://reviews.llvm.org/D107261

(cherry picked from commit ce49fd024b43bd76b149f984b8f0d16e92b9bb06)
---
 clang/lib/Driver/ToolChains/MinGW.cpp | 7 +++++--
 clang/test/Driver/mingw.cpp           | 7 +++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/MinGW.cpp b/clang/lib/Driver/ToolChains/MinGW.cpp
index 20efbdc237a840..7ba729f36bd87a 100644
--- a/clang/lib/Driver/ToolChains/MinGW.cpp
+++ b/clang/lib/Driver/ToolChains/MinGW.cpp
@@ -136,10 +136,13 @@ void tools::MinGW::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     llvm_unreachable("Unsupported target architecture.");
   }
 
-  if (Args.hasArg(options::OPT_mwindows)) {
+  Arg *SubsysArg =
+      Args.getLastArg(options::OPT_mwindows, options::OPT_mconsole);
+  if (SubsysArg && SubsysArg->getOption().matches(options::OPT_mwindows)) {
     CmdArgs.push_back("--subsystem");
     CmdArgs.push_back("windows");
-  } else if (Args.hasArg(options::OPT_mconsole)) {
+  } else if (SubsysArg &&
+             SubsysArg->getOption().matches(options::OPT_mconsole)) {
     CmdArgs.push_back("--subsystem");
     CmdArgs.push_back("console");
   }
diff --git a/clang/test/Driver/mingw.cpp b/clang/test/Driver/mingw.cpp
index 796bde8eebe4c8..83b61ba7d33f0d 100644
--- a/clang/test/Driver/mingw.cpp
+++ b/clang/test/Driver/mingw.cpp
@@ -61,3 +61,10 @@
 // RUN: %clang -target i686-windows-gnu -E -### %s -municode 2>&1 | FileCheck -check-prefix=CHECK_MINGW_UNICODE %s
 // CHECK_MINGW_NO_UNICODE-NOT: "-DUNICODE"
 // CHECK_MINGW_UNICODE: "-DUNICODE"
+
+// RUN: %clang -target i686-windows-gnu -### %s 2>&1 | FileCheck -check-prefix=CHECK_NO_SUBSYS %s
+// RUN: %clang -target i686-windows-gnu -### %s -mwindows -mconsole 2>&1 | FileCheck -check-prefix=CHECK_SUBSYS_CONSOLE %s
+// RUN: %clang -target i686-windows-gnu -### %s -mconsole -mwindows 2>&1 | FileCheck -check-prefix=CHECK_SUBSYS_WINDOWS %s
+// CHECK_NO_SUBSYS-NOT: "--subsystem"
+// CHECK_SUBSYS_CONSOLE: "--subsystem" "console"
+// CHECK_SUBSYS_WINDOWS: "--subsystem" "windows"